The invention relates to a plant as well as a method for transporting textile fabrics, as well as to a plant and a method for manufacturing nonwoven mats.
Such plants are known from the European Patent EP 0 817 875 A, for example. In the known plant, at least one nonwoven mat is mechanically delivered onto a permeable and suctioned conveyor belt particularly suctioned at the point of delivery by means of a suction box. A disadvantage thereof is that for suctioning the conveyor belt, several suction means arranged over the length of the conveyor belt are required, the suction intensities of which have to be coordinated and which lead to high energy consumption.
It is the object of the present invention to provide a plant and a method for transporting textile fabrics and for manufacturing nonwoven mats, respectively, which permit the transport of textile fabrics even at high transport speeds without permanent under suction by suction means.
This object is solved according to the present invention. The invention advantageously provides that several air guiding means extending transversely to the conveyor belt are arranged on the side of the conveyor belt facing away from the textile fabrics, said air guiding means deflecting the air entrained by the conveyor belt on the side facing away from the textile fabrics. The invention advantageously permits the transport of textile fabrics at a high transport speed of more than 100 m/min without a permanent suctioning of the conveyor belts by the use of suction means at their lower surface. The suction airflow required for the transport at high transport speeds is achieved by solely deflecting the air entrained on the lower surface of the conveyor belt. This results in a proportional connection between the conveyor belt speed and the adhesion of the textile fabric on the conveyor belt. Since the plant does not need any suction means, the requirement of regulating the suction means is eliminated. Moreover, the power consumption of the suction means is eliminated so that not only the costs of the plant but also the operational costs can be reduced.
The edge of the air guiding means facing the conveyor belt extends at a short, preferably adjustable, distance to the conveyor belt. The short distance of the air guiding means to the conveyor belt guarantees that the far prevalent portion of the air entrained on the lower surface of the conveyor belt is able to be deflected to achieve the desired airflow through the textile fabric and the conveyor belt. Due to the fact that the distance is adjustable, it is possible to adjust the suction power. Preferably, however, a distance between 0.1 and 10 mm is set.
Preferably, the air guiding means are stationarily mounted on a supporting structure extending at a distance from the conveyor belt or, alternatively, mounted so as to be displaced parallel to and in longitudinal direction of the conveyor belt. The parallel displacement of the air guiding means in longitudinal direction of the conveyor belt also permits an individual adaptation of the airflow to specific requirements in certain route sections of the conveyor belt. Preferably, the air guiding means are equally spaced from each other in transport direction.
In a preferred embodiment, the air guiding means are adapted to be pivoted about an axis extending parallel to the conveyor belt and transversely to the transport direction. Thus, the distance of the air guiding means to the conveyor belt is adjustable in a simple and quick manner.
In one embodiment, it is provided that the air guiding means are arranged only in the border portion of the conveyor belt. In this case, the textile fabric is retained on the conveyor belt by its suctioned border portions in particular.
According to another embodiment, it may be provided that air guiding means are provided over the entire working width of the conveyor belt or only in the border portion in alternating arrangement. It is possible to arrange several air guiding means of the same type behind one another.
The air guiding means may extend at an angle of approximately 5 to 90xc2x0 relative to the plane of movement of the conveyor belt.
According to a preferred embodiment, the air guiding means have an aerodynamic wing profile in cross section. The aerodynamic wing shape supports the deflection of the air entrained by the conveyor belt and thereby increases the suction power and thus the adhesion of the textile fabric on the conveyor belt.
According to another embodiment, it is provided that the air guiding means extending over the entire working width extend, in top view, in the shape of an arrow, and the tip of the arrow may be arranged in the center of the conveyor belt. Such a design of the air guiding means permits to produce an additional transverse component of the airflow. According to another alternative, it is also possible to provide the arrow-shaped arrangement of the air guiding means only in the border portion when seen in top view.
Preferably, it is provided that wing-shaped air deflectors are arranged below the conveyor belt in front of deflection areas where the conveyor belt is deflected, or at delivery points where the conveyor belt receives the textile fabric. The air deflectors prevent air swirls in the deflection areas and at the delivery points.
Moreover, air stripping means, e.g., in the form of a doctor blade, may be arranged on rotating parts to avoid drag air of the rotating part.
Such air stripping means, for example, are arranged on the deflecting rollers of the conveyor belt to avoid that the drag air entrained by the deflecting rollers generates an airflow from below toward the conveyor belt.
It is possible to adjust several air guiding means together in groups. The angle and the distance of the air guiding means to the conveyor belt and/or the mutual distance of the air guiding means in transport direction may be automatically adjustable in dependence on the transport speed and/or the mass per unit area and/or the fiber specification of the textile fabrics.
In the gaps between the air guiding means, a suction airflow can be produced by a suction means in the region of the delivery points, where the textile fabric is conveyed to the conveyor belt, for a short interval of time in order to support the starting process. Such a suction means can support the adhesion of the textile fabric during the starting operation and it is switched off when the transport speed is reached or already before, as from a transport speed of 80 m/min, for example.
Furthermore, the invention relates to a plant for manufacturing nonwoven mats, with a least one card and with at least one suctioned permeable conveyor belt for the transport of the nonwoven mat produced by the card, this plant being provided with a transport plant.
In this case, the conveyor belt can transport a mechanically produced nonwoven mat or an aerodynamically produced nonwoven mat.
The plant for manufacturing nonwoven mats can also convey several nonwoven mats on top of each other to a single conveyor belt.
In this case, the nonwoven mats can be produced by different cards or come from a double doffer card, one conveyor belt taking over one nonwoven mat, respectively. An upper nonwoven mat is then conveyed by an upper conveyor belt onto a lower nonwoven mat on a lower conveyor belt and fixed on the underlying nonwoven mat by the airflow through the conveyor belt.
The arrangement of two conveyor belts on top of each other has the additional advantage that the air flowing through the upper conveyor belt, which is led through the lower conveyor belt as well, is equalized to a high degree, whereby the danger of air whirls is strongly decreased.
The inventive method for transporting textile fabrics with a permeable and suctioned conveyor belt by delivering a textile fabric onto the moved conveyor belt provides that an increased contact pressure force against the textile fabric is generated by deflecting the drag air entrained on the lower surface of the conveyor belt.